1. Nomenclature

2. Properties
    Zeta¹ Cancri  Zeta² Cancri 

3. References

Zeta Cancri (ζ Cancri, abbreviated Zeta Cnc, ζ Cnc) is a multiple star system in the constellation of Cancer. It is approximately 83.4 light-years from Earth, and has a combined apparent magnitude of +4.67. Since it is near the ecliptic, it can be occulted by the Moon and, very rarely, by planets.

The system is constituted as follows:^[1]

• A binary pair designated Zeta¹ Cancri or alternatively Zeta Cancri AB, the two components of which are themselves designated Zeta¹ Cancri A or simply Zeta Cancri A (and also named Tegmine^[2]) and Zeta¹/Zeta Cancri B.
• A triple star system designated Zeta² Cancri or alternatively Zeta Cancri C, consisting of a single star primary, designated Zeta²/Zeta Cancri Ca, together with a secondary binary pair, designated Zeta²/Zeta Cancri Cb. The binary pair's two components are themselves designated Zeta²/Zeta Cancri Cb1 and Cb2.

Nomenclature

Considerable confusion had developed concerning the catalogue identities of the three bright stars; correct correspondences were worked out by Griffin:^[4]

In Chinese, {{lang|zh|水位}} ({{lang|zh-Latn|Shuǐ Wèi}}), meaning Water Level, refers to an asterism consisting of Zeta Cancri, 6 Canis Minoris, 11 Canis Minoris and 8 Cancri.^[6] Consequently, Zeta Cancri itself is known as {{lang|zh|水位四}} ({{lang|zh-Latn|Shuǐ Wèi sì}}, {{lang-en|the Fourth Star of Water Level}}).^[7]

Properties

Zeta Cancri can be resolved as a binary star in small telescopes. Its binary nature was discovered in 1756 by Johann Tobias Mayer. William Herschel resolved the two components that make up Zeta¹ Cancri in 1781. As early as 1831, John Herschel noticed perturbations in Zeta² Cancri's orbit around Zeta¹; this led Otto Wilhelm von Struve, in 1871, to postulate a fourth, unseen, component which orbited closely the visible member of Zeta².^[4] Later observations have resolved this fourth component and have indicated that there may be one or two more unobserved components.^[11][12]

Zeta¹ and Zeta² Cancri are 5.06 arcseconds apart. These two star systems orbit around their common centre of mass once every 1100 years. The radius is about 6.80.{{huh|date=September 2018}}

Zeta¹ Cancri

The two components are both yellow-white main sequence dwarfs of spectral class F. The apparent magnitudes of A and B are +5.58 and +5.99, respectively. They are separated, as of 2008, by 1 arcsecond, requiring a large telescope to resolve them, but this separation will increase until the year 2020. They complete one orbit every 59.6 years.^[13] The estimated masses for the pair are 1.28 and 1.18 solar masses, respectively.

Zeta² Cancri

Zeta Cancri Ca is the brightest of the three components, having an apparent magnitude of +6.12. It appears to be a yellow G-type star, often reported as G5V, but now thought to be earlier, probably G0V. This star has around 1.15 solar masses. The tenth magnitude Zeta Cancri Cb is a close pair of red dwarfs. The separation between Ca and Cb is approximately 0.3 arcseconds, and their orbital period is 17 years.

References

• Banu Alfageer
• Banu Al-naḌir
• Banu Avar
• Banu bakr
• Banu bakr ibn abd manat
• Banuelos
• Banuelos de Bureba
• Banuelos de Bureba, Burgos
• Banuelos de Bureba, Spain
• Banuelos, Guadalajara
• Banuelos, Spain
• Banu Ghassan
• Banu Goshasp
• Banugues
• Banu Hamadan
• Banu Hudhayl
• Banu Israil
• Banu Ka'b
• Banu Kainuka'a
• Banu Kinanah
• Banu Kuraiẓa
• Banu Lam
• Banu Main Teri Dulhan
• Banu Malik
• Banumarin dynasty